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History

~900

first mining activities.

~1300

start of wire production.

Description

The Hemer Felsenmeer, literally sea of rocks at Hemer, is a
Natural Monument with strange and interesting rock formations.
It is interesting from two completely different views, the speleologic and the
mining archaeology view.

To reach the area you best start at the show cave
Heinrichshöhle
where a single lane track called Felsenmeerstraße leads up into the
forest.
It is about ten minutes walk to the Felsenmeer.
This area is about 700m long, up to 200m wide and 45m above the valley.
It is distinguished into three parts, the Großes Felsenmeer (Big
Felsenmeer), the Kleines Felsenmeer (small Felsenmeer) and the
Paradies (paradise).

The Big Felsenmeer area is interpreted as a huge solution doline, an area where
meteoric water penetrating the cracks in the limestone created clefts filled
with residuals like clay.
The middle Devonian limestone was formed as a reef, the cracks are a result of
tectonic movements.
Rather uncommon for karst areas is the upwelling of hot thermal water and gases
from below, depositing chemically diverse ores and minerals in the cracks.
The ores include hematite (iron ore), calamine (zinc ore), brown
iron ore, and rare green lead ore.
Mineral collectors still find interesting minerals outside the protected area.
However, the most important metal in the ores was iron.

archaeological excavations proofed mining activities as early as 900 AD.
This is the oldest iron mining in the Sauerland.
It was favoured by the rich forests of the area which was used to produce heat
for the mining and charcoal for the smelting.
The oldest mining technique used here was heating the ore by burning wood piles
in front and cooling it down abruptly with cold water.
The ore got cracks and was much easier to mine.

The mined ore was smelted on location with simple bloomery furnaces.
The resulting raw iron was smelted a second time and formed into an
Osemund, a typical bar.
From the 14th century wires were produced in the area.
First by hammering the Osemund, later by drewing the the wire through a gouge.
For the developing wire industry the water power of the rivers was important
too.
When techniques were developed to process the iron with water power, all around
along the rivers small mills, smiths, and factories were founded.
The history of the iron industrie around the Felsenmeer is on display in the
Felsenmeer Museum in Hemer.